JP6780581B2 - Rotating body pressing mechanism and image forming apparatus equipped with it - Google Patents

Description

The present invention relates to a rotating body pressing mechanism and an image forming apparatus provided with the same, and in particular, press-contacts the first rotating body, the second rotating body that presses against the first rotating body, and the second rotating body. The present invention relates to a third rotating body, a rotating body pressing mechanism having the third rotating body, and an image forming apparatus provided with the same.

Conventionally, a charging roller that is pressed against a photoconductor drum (image carrier) that carries a toner image and charges the photoconductor drum, a cleaning roller that is pressed against the charging roller and cleans the surface of the charging roller, and a charging roller. Image formation including a contact charging type charging device having a bearing member that rotatably supports the rotating shaft of the cleaning roller and the rotating shaft of the cleaning roller, and an urging member that urges the bearing member toward the photoconductor drum. The device is known.

In such a charging device, the bearing member supports, for example, the rotating shaft of the charging roller and the rotating shaft of the cleaning roller at regular intervals so that the pressure contact force of the cleaning roller with respect to the charging roller becomes a predetermined magnitude. doing. Therefore, the pressure contact force of the cleaning roller with respect to the charging roller is determined by the distance between the rotation axis of the charging roller and the rotation axis of the cleaning roller, and the pressure contact force of the charging roller with respect to the photoconductor drum is determined by the urging force of the urging member. Will be done.

The charging roller that charges the photoconductor drum, the cleaning roller that cleans the surface of the charging roller, the bearing member that rotatably supports the rotating shaft of the charging roller and the rotating shaft of the cleaning roller, and the bearing member are the photoconductor drum. A charging device including an urging member for urging toward is disclosed in, for example, Patent Document 1.

Japanese Unexamined Patent Publication No. 2013-167913

By the way, in a contact charging type charging device, permanent strain may occur in the elastic member of the charging roller due to the pressure contact force with respect to the photoconductor drum. In order to suppress this permanent strain, it is advantageous to increase the thickness of the elastic member.

However, when increasing the thickness of the elastic member of the charging roller, it is necessary to reduce the diameter of the rotating shaft of the charging roller. Therefore, there is a problem that the rotating shaft of the charging roller bends when both ends of the rotating shaft of the charging roller are urged toward the photoconductor drum. In this case, since the pressure contact force at the center of the charging roller in the axial direction (longitudinal direction) is smaller than the pressure contact force at both ends, uneven charging occurs in the photoconductor drum in the axial direction.

The present invention has been made to solve the above problems, and an object of the present invention is to prevent the second rotating body from bending while ensuring the pressure contact force of the second rotating body with respect to the first rotating body. It is an object of the present invention to provide a rotating body pressing mechanism capable of suppressing and an image forming apparatus provided with the mechanism.

In order to achieve the above object, the rotating body pressing mechanism of the first configuration of the present invention includes a first rotating body, a second rotating body that presses against the first rotating body with a first pressure contact force, and a second rotating body. The third rotating body that presses against the rotating body with the second pressure contact force, the first urging member that biases the third rotating body toward the second rotating body, and the second rotating body are the second rotating body. The first guide member and the third rotating body that movably guide along the first pressure contact direction, which is the direction in which the third rotating body is pressed against the first rotating body, are pressed against the second rotating body. A second guide member for movably guiding along the second pressure contact direction, which is the direction in which the body is driven, is provided. The second rotating body is pressed against the first rotating body by utilizing the second pressure contact force.

According to the rotating body pressing mechanism of the first configuration of the present invention, the first guide member for movably guiding the second rotating body along the first pressure contact direction and the third rotating body along the second pressure contact direction. A second guide member for movably guiding the second rotating body is provided, and the second rotating body is in pressure contact with the first rotating body by utilizing the second pressure contact force. As a result, in order to obtain the required pressure contact force (first pressure contact force) of the second rotating body with respect to the first rotating body, it is not necessary to urge both ends of the second rotating body with a force equal to the first pressure contact force. .. That is, the force for urging both ends of the second rotating body can be reduced as compared with the case where the second rotating body is in pressure contact with the first rotating body without utilizing the second pressure contact force. Therefore, it is possible to suppress the bending of the second rotating body while ensuring the pressure contact force of the second rotating body with respect to the first rotating body.

It is the schematic which shows the structure of the image forming apparatus provided with the rotating body pressing mechanism of 1st Embodiment of this invention. It is a top view which shows the structure of the photoconductor drum, the charging roller and the cleaning roller of the rotating body pressing mechanism of 1st Embodiment of this invention. It is a side view which shows the structure of the rotating body pressing mechanism of 1st Embodiment of this invention. It is a figure which shows the structure around the end of the charging roller and the cleaning roller of the rotating body pressing mechanism of 1st Embodiment of this invention. It is a side view which shows the structure of the rotating body pressing mechanism of 2nd Embodiment of this invention. It is a side view which shows the structure of the rotating body pressing mechanism of 3rd Embodiment of this invention. It is a figure for demonstrating the 1st pressure contact force and the 2nd pressure contact force acting on the rotating body pressing mechanism of 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)
The image forming apparatus 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4. As shown in FIG. 1, an image forming unit P is arranged in the image forming apparatus 1 (here, a monochrome printer). The image forming unit P forms a predetermined image by each step of charging, exposure, developing, and transferring.

A photoconductor drum (image carrier) 2 that supports a visible image (toner image) is disposed in the image forming unit P, and the toner image formed on the photoconductor drum 2 is a sheet (recording medium). ) 6 is transferred onto the sheet 6 and then fixed on the sheet 6 in the fixing unit 7, and then discharged from the main body of the apparatus.

Next, the image forming unit P will be described in detail. Around the photoconductor drum 2 rotatably arranged, a charging device 3 for charging the photoconductor drum 2, an exposure unit 4 for exposing image information to the photoconductor drum 2, and a photoconductor drum 2 A developing unit 5 for forming a toner image, a cleaning device 9 for collecting the developer (toner) remaining on the photoconductor drum 2, and a static eliminator 10 for removing the electrostatic latent image are provided. ..

First, the surface of the photoconductor drum 2 is uniformly charged by the charging device 3, and then light is irradiated by the exposure unit 4 to form an electrostatic latent image corresponding to the image signal on the photoconductor drum 2. The toner of the developing unit 5 is supplied to the surface of the photoconductor drum 2 and electrostatically adheres to form a toner image corresponding to the electrostatic latent image formed by the exposure from the exposure unit 4. The details of the charging device 3 will be described later.

The sheet 6 on which the toner image is transferred is housed in a paper feed cassette 12 that houses the sheet 6, and is directed toward the photoconductor drum 2 on which the toner image is formed via the paper feed roller 13 and the resist roller pair 14. Is transported. Then, the toner image on the photoconductor drum 2 is transferred onto the sheet 6 by the transfer roller 17.

The sheet 6 to which the toner image is transferred is conveyed to the fixing unit 7. Further, in the photoconductor drum 2 after the toner image is transferred, the toner remaining on the surface of the photoconductor drum 2 is recovered by the cleaning device 9 in preparation for the subsequent formation of a new electrostatic latent image. The sheet 6 conveyed to the fixing unit 7 is heated and pressurized by a pair of fixing rollers to fix a toner image on the surface of the sheet 6 to form a predetermined image. The sheet 6 on which the image is formed is then discharged to the discharge tray 19 by the discharge roller pair 18.

Next, the detailed structure around the charging device 3 will be described.

As shown in FIG. 2, the charging device 3 has a charging roller (second rotating body) 31 and a cleaning roller (third rotating body) 32. The charging roller 31 presses against the photoconductor drum (first rotating body, image carrier) 2 and rotates in a driven manner to uniformly charge the surface of the photoconductor drum 2 to a predetermined potential. As the photoconductor drum 2, for example, one in which a photosensitive layer made of amorphous silicon (a-Si) or the like is laminated on the surface of an aluminum drum can be used. Further, the photoconductor drum 2 is connected to a drum drive motor via a drive gear (not shown), and rotates clockwise in FIG. 1.

As the charging roller 31, for example, a solid type such as a conductive rubber roller in which a rubber layer (elastic layer) 31b made of epichlorohydrin rubber or the like is formed on the peripheral surface of a metal shaft (core metal) 31a can be preferably used. However, it is not particularly limited to this. In addition, for example, a sponge type in which a foam rubber roller is covered with a tube can also be used.

The cleaning roller 32 is pressed against the surface of the charging roller 31 to clean the surface of the charging roller 31. The cleaning roller 32 is a brush roller provided with a brush portion 32b for cleaning the surface of the charging roller 31 on the peripheral surface of the metal shaft (core metal) 32a. The cleaning roller 32 is connected to the drum drive motor described above via a drive gear (not shown), and is adapted to rotate clockwise in FIG. 1.

As the material of the brush portion 32b, for example, a conductive resin material such as nylon or polyester can be used, but in addition, conductivity is imparted by combining the resin material with another conductive material. Such materials can also be used. The cleaning roller 32 may not be a brush roller, but may be a roller using an elastically deformable pad such as sponge-like rubber, resin, or synthetic fiber felt instead of the brush portion 32b.

Bearing members 34 and 35 are attached to both ends of the shaft 31a of the charging roller 31 and both ends of the shaft 32a of the cleaning roller 32, respectively, as shown in FIG. The bearing members 34 and 35 are supported by a sheet metal guide member (first guide member, second guide member) 37. The guide member 37 is formed with elongated guide holes 37a and 37b into which the bearing members 34 and 35 are inserted, respectively. The guide holes 37a and 37b are formed so as to extend toward the rotation axis 2a of the photoconductor drum 2.

Bearing members 36 are attached to both ends of the rotating shaft 2a of the photoconductor drum 2, and the guide member 37 is provided with insertion holes 37c into which the bearing member 36 is rotatably inserted. Since the insertion hole 37c is formed in a perfect circle, the distance from each part of the guide member 37 (for example, the guide holes 37a and 37b) to the photoconductor drum 2 is constant.

The guide holes 37a and 37b and the insertion holes 37c are arranged on the same straight line. Therefore, the shafts 31a and 32a and the rotating shaft 2a are also arranged on the same straight line.

Further, the guide hole 37a supports the charging roller 31 so as to be rotatable and slidable toward the rotating shaft 2a of the photoconductor drum 2. The guide hole 37b supports the cleaning roller 32 so as to be rotatable and slidable toward the shaft 31a of the charging roller 31. That is, the guide member 37 guides the charging roller 31 so as to be movable along the first pressure contact direction (arrow A direction), which is the direction in which the charging roller 31 is in pressure contact with the photoconductor drum 2, and the cleaning roller 32. Is movably guided along the second pressure contact direction (arrow A direction), which is the direction in which the cleaning roller 32 is in pressure contact with the charging roller 31.

Both ends (or bearing members 34) of the shaft 31a of the charging roller 31 are urged toward the photoconductor drum 2 by a charging roller urging member (second urging member) 41 made of a compression coil spring or the like. The charging roller urging member 41 is arranged between the shaft 31a (or bearing member 34) of the charging roller 31 and the urging member support portion (not shown) of the guide member 37. The charging roller urging member 41 may be arranged between the shaft 31a (or bearing member 34) of the charging roller 31 and the urging member support portion (not shown) of the image forming apparatus 1 main body.

Both ends (or bearing members 35) of the shaft 32a of the cleaning roller 32 are urged toward the charging roller 31 by a cleaning roller urging member (first urging member) 42 made of a compression coil spring or the like. The cleaning roller urging member 42 is arranged between the shaft 32a (or bearing member 35) of the cleaning roller 32 and the urging member support portion (not shown) of the guide member 37. The cleaning roller urging member 42 may be arranged between the shaft 32a (or bearing member 35) of the cleaning roller 32 and the urging member support portion (not shown) of the image forming apparatus 1 main body.

The rotating body pressing mechanism of the present invention is composed of the photoconductor drum 2, the charging roller 31, the cleaning roller 32, the guide member 37, the charging roller urging member 41, and the cleaning roller urging member 42.

The cleaning roller 32 is pressed against the charging roller 31 with a predetermined pressure contact force (second pressure contact force) by the urging force of the cleaning roller urging member 42.

The charging roller 31 has a predetermined pressure contact force (first pressure contact force) by the urging force of the charging roller urging member 41 and the pressure contact force from the cleaning roller 32 (here, a force having the same magnitude as the second pressure contact force). Is in pressure contact with the photoconductor drum 2. Specifically, as shown in FIG. 4, the cleaning roller urging member 42 urges both ends of the cleaning roller 32 (arrow F42), so that the brush portion 32b of the cleaning roller 32 becomes the rubber layer of the charging roller 31. Press 31b (arrow F32). Then, the charging roller 31 is subjected to the charging roller urging member 41 by the amount obtained by subtracting the pressure contact force by the brush portion 32b of the cleaning roller 32 from the required pressure contact force (first pressure contact force) of the charging roller 31 with respect to the photoconductor drum 2. Both ends are urged (arrow F41). In this way, the second pressure contact force also acts on the pressure contact of the charging roller 31 with respect to the photoconductor drum 2, and the charging roller 31 presses against the photoconductor drum 2 using the second pressure contact force. The pressure contact force (first pressure contact force) of the charging roller 31 with respect to the photoconductor drum 2 is larger than the pressure contact force (second pressure contact force) of the cleaning roller 32 with respect to the charging roller 31.

In the present embodiment, as described above, the charging roller 31 is guided so as to be movable along the first pressure contact direction (arrow A direction), and the cleaning roller 32 is moved along the second pressure contact direction (arrow A direction). The charging roller 31 includes a guide member 37 that guides the photoconductor drum 2 by pressing the second pressure contact force. As a result, in order to obtain the required pressure contact force (first pressure contact force) of the charging roller 31 with respect to the photoconductor drum 2, it is not necessary to urge both ends of the charging roller 31 with a force equal to the first pressure contact force. That is, the force for urging both ends of the charging roller 31 can be reduced as compared with the case where the charging roller 31 presses against the photoconductor drum 2 without utilizing the second pressure contact force. Therefore, it is possible to suppress the bending of the charging roller 31 while ensuring the pressure contact force of the charging roller 31 with respect to the photoconductor drum 2.

As a result, it is possible to prevent the photoconductor drum 2 from being charged unevenly in the axial direction (longitudinal direction). Further, since the diameter of the shaft 31a of the charging roller 31 can be reduced and the thickness of the rubber layer 31b of the charging roller 31 can be increased, the rubber layer 31b of the charging roller 31 can be formed due to the pressure contact force with respect to the photoconductor drum 2. It is possible to suppress the occurrence of permanent strain.

Further, as described above, the charging roller 31 and the cleaning roller 32 are guided by one guide member 37. As a result, it is possible to suppress an increase in the number of parts and to make the rotating body pressing mechanism a simple structure.

Further, as described above, the photoconductor drum 2 is rotatably attached to the guide member 37. As a result, the guide member 37 does not move in the pressure contact direction (arrow A direction) with respect to the photoconductor drum 2, so that the second pressure contact force can be easily applied to the pressure contact of the charging roller 31 with respect to the photoconductor drum 2.

Further, as described above, the cleaning roller urging member 42 is arranged between the guide member 37 and the cleaning roller 32. As a result, the rotating body pressing mechanism can be made into a simpler structure.

Further, as described above, the charging roller urging member 41 is arranged between the guide member 37 and the charging roller 31. As a result, the rotating body pressing mechanism can be made into a simpler structure.

Further, as described above, when the required pressure contact force (first pressure contact force) of the charging roller 31 with respect to the photoconductor drum 2 is larger than the second pressure contact force, the charging roller 31 is provided by providing the charging roller urging member 41. The required pressure contact force (first pressure contact force) with respect to the photoconductor drum 2 can be easily obtained.

(Second Embodiment)
In the second embodiment, the required pressure contact force (first pressure contact force) of the charging roller 31 with respect to the photoconductor drum 2 and the required pressure contact force (second pressure contact force) of the cleaning roller 32 with respect to the charging roller 31 are equal in magnitude. The case where this is the case will be described.

In the present embodiment, as shown in FIG. 5, the guide member 37 is formed with an elongated guide hole 37d into which the bearing members 34 and 35 are inserted. The guide hole 37d is formed so as to extend toward the rotation axis 2a of the photoconductor drum 2. Therefore, the shaft 31a of the charging roller 31, the shaft 32a of the cleaning roller 32, and the rotating shaft 2a of the photoconductor drum 2 are arranged on the same straight line as in the first embodiment.

Both ends (or bearing members 35) of the shaft 32a of the cleaning roller 32 are urged toward the charging roller 31 by the cleaning roller urging member 42, as in the first embodiment.

On the other hand, unlike the first embodiment, the charging roller urging member 41 for urging both ends (or bearing members 34) of the shaft 31a of the charging roller 31 is not provided. The charging roller 31 is in pressure contact with the photoconductor drum 2 by a pressure contact force from the cleaning roller 32 (here, a force having the same magnitude as the second pressure contact force).

The other structures of the second embodiment are the same as those of the first embodiment.

In the present embodiment, as described above, when the required pressure contact force (first pressure contact force) of the charging roller 31 with respect to the photoconductor drum 2 is equal to the second pressure contact force, the photoconductor drum 2 and the charging roller 31 By arranging the cleaning roller 32 and the cleaning roller 32 on the same straight line, the cleaning roller 32 can be pressure-welded with the pressure contact force (second pressure contact force) required for the charging roller 31 only by the urging force of the cleaning roller urging member 42. At the same time, the charging roller 31 can be pressure-welded with the pressure contact force (first pressure contact force) required for the photoconductor drum 2.

Other effects of the second embodiment are the same as those of the first embodiment.

(Third Embodiment)
In the third embodiment, the case where the required pressure contact force (first pressure contact force) of the charging roller 31 with respect to the photoconductor drum 2 is smaller than the required pressure contact force (second pressure contact force) of the cleaning roller 32 with respect to the charging roller 31. explain.

In the present embodiment, as shown in FIG. 6, the guide member 37 is formed with elongated guide holes 37a and 37b into which the bearing members 34 and 35 are inserted, respectively. The guide hole 37a is formed so as to extend toward the rotation shaft 2a of the photoconductor drum 2, while the guide hole 37b is not formed so as to extend toward the rotation shaft 2a of the photoconductor drum 2. The guide holes 37a, 37b and the insertion hole 37c are not arranged on the same straight line, and the shafts 31a, 32a and the rotating shaft 2a are not arranged on the same straight line.

The first pressure contact direction (arrow A direction), which is the direction in which the charging roller 31 presses against the photoconductor drum 2, is the second pressure contact direction (arrow B direction), which is the direction in which the cleaning roller 32 presses against the charging roller 31. ) And the direction of intersection.

Both ends (or bearing members 35) of the shaft 32a of the cleaning roller 32 are urged toward the charging roller 31 by the cleaning roller urging member 42, as in the first and second embodiments.

On the other hand, as in the second embodiment, the charging roller urging member 41 for urging both ends (or bearing members 34) of the shaft 31a of the charging roller 31 is not provided. The charging roller 31 is in pressure contact with the photoconductor drum 2 by the pressure contact force from the cleaning roller 32. Specifically, as shown in FIG. 7, the required pressure contact force (first pressure contact force, arrow F31) of the charging roller 31 with respect to the photoconductor drum 2 is the pressure contact force required with respect to the charging roller 31 of the cleaning roller 32. (Second pressure contact force, arrow F32) is configured to be equal to the component in the first pressure contact direction (arrow F32a).

The other structures of the third embodiment are the same as those of the first and second embodiments.

In the present embodiment, as described above, when the required pressure contact force (first pressure contact force) of the charging roller 31 with respect to the photoconductor drum 2 is smaller than the second pressure contact force, the first pressure contact force is the second pressure contact force. By arranging the photoconductor drum 2, the charging roller 31 and the cleaning roller 32 so as to be equal to the components in the pressure contact direction, the cleaning roller 32 is required for the charging roller 31 only by the urging force of the cleaning roller urging member 42. The pressure contact force (second pressure contact force) can be used for pressure contact, and the charging roller 31 can be pressure contacted with the pressure contact force (first pressure contact force) required for the photoconductor drum 2.

Other effects of the third embodiment are the same as those of the first embodiment.

It should be noted that the embodiments disclosed this time are exemplary in all respects and are not considered to be restrictive. The scope of the present invention is shown by the scope of claims rather than the description of the above-described embodiment, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

For example, an example in which the present invention is applied to a printer has been shown, but the present invention is not limited to this. Needless to say, a rotation having a first rotating body, a second rotating body that presses against the first rotating body, and a third rotating body that presses against the second rotating body, such as a copying machine and a composite machine. The present invention can be applied to various image forming devices provided with a body pressing mechanism.

Further, in the above embodiment, an example in which the photoconductor drum 2, the charging roller 31 and the cleaning roller 32 are used as the first rotating body, the second rotating body and the third rotating body has been shown, but the present invention is not limited to this. .. For example, as the first rotating body, the second rotating body, and the third rotating body, a toner layer thickness regulation that regulates the thickness of a photoconductor drum, a cleaning roller that cleans the surface of the photoconductor drum, and a toner layer on the surface of the cleaning roller. Rollers may be used. Further, for example, as the first rotating body, the second rotating body and the third rotating body, the surfaces of the first decal roller made of a metal roller, the second decal roller made of an elastic roller having an elastic layer, and the second decal roller A cleaning roller for cleaning may be used.

Further, in the above embodiment, an example in which the first guide member for guiding the second rotating body and the second guide member for guiding the third rotating body are integrally provided has been described, but the first guide member and the second guide member are provided. The guide member may be provided separately.

1 Image forming device 2 Photoreceptor drum (first rotating body, image carrier)
31 Charging roller (second rotating body)
32 Cleaning roller (3rd rotating body)
37 Guide member (1st guide member, 2nd guide member)
41 Charging roller urging member (second urging member)
42 Cleaning roller urging member (first urging member)

Claims (7)

The first rotating body and
A second rotating body that is pressed against the first rotating body with the first pressure contact force, and
A third rotating body that is pressed against the second rotating body with a second pressure contact force,
A first urging member that urges the third rotating body toward the second rotating body, and
A first guide member that movably guides the second rotating body along the first pressure contact direction, which is the direction in which the second rotating body is in pressure contact with the first rotating body.
A second guide member that movably guides the third rotating body along the second pressure contact direction, which is the direction in which the third rotating body is in pressure contact with the second rotating body.
With
The second rotating body is pressed against the first rotating body by utilizing the second pressure contact force .
The first pressure contact force is smaller than the second pressure contact force.
The first rotating body, the second rotating body, and the third rotating body are not arranged on the same straight line.
The rotating body pressing mechanism, characterized in that the first pressure contact force is equal to a component of the second pressure contact force in the first pressure contact direction . The rotating body pressing mechanism according to claim 1, wherein the first guide member is provided integrally with the second guide member. The rotating body pressing mechanism according to claim 2, wherein the first rotating body is rotatably attached to the first guide member. The rotating body pressing mechanism according to claim 3, wherein the first urging member is arranged between the second guide member and the third rotating body. The first rotating body is an image carrier that supports a toner image.
The second rotating body is a charging roller that charges the image carrier.
The rotating body pressing mechanism according to any one of claims 1 to 4 , wherein the third rotating body is a cleaning roller that cleans the surface of the charging roller. The first rotating body is an image carrier that supports a toner image.
The second rotating body is a cleaning roller that cleans the surface of the image carrier.
The rotating body pressing mechanism according to any one of claims 1 to 4 , wherein the third rotating body is a toner layer thickness regulating roller that regulates the thickness of the toner layer on the surface of the cleaning roller. An image forming apparatus comprising the rotating body pressing mechanism according to any one of claims 1 to 6 .

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